What does imprinting involve concerning gene expression?

Imprinting refers to a specific epigenetic phenomenon where one allele of a gene is silenced while the other is expressed, primarily through the process of DNA methylation. This means that in certain genes, only the allele inherited from one parent (either maternal or paternal) is actively transcribed, while the other allele is marked and rendered inactive. This selective gene expression is crucial for normal development and can have significant implications for growth and metabolic processes.

Methylation involves the addition of methyl groups to the DNA, often at cytosine residues, leading to chromatin changes that inhibit gene transcription. Because of this mechanism, imprinted genes can affect various traits and disorders, illustrating the importance of parental origin in gene expression.

This dynamic underlies many phenomena in genetics, including certain genetic disorders linked to imprinting. Understanding imprinting is essential for comprehending how epigenetic factors influence development and disease.